Power transmission



June 1942. F, T. HARRINGTON ETAL 7 2,285,968

' POWER TRANSMISSION Filed Sept. 50, 1940 FEED ON OFF STOP OFF INVENTORS FERRIS T. HARRINGTON & RALPH L. TWEEDALE BY A ATTORNEY 2,285,968 rowan mmsmssros umrso STATES,- PATENT oFFics- Ferris T.

nand Ralph L. Tweedale,

Harrlngto Detroit, Hicln, assignors to Vickers Incorporated, Detroit, men, a corporation of Michigan Application September so, 1940, Serial No. 359,016

2 claim. (on. co -'52) This invention relates to power transmissions.

particularly to those of the type comprising two or more fluid pressure energy translating devices, one of which may function as a pump and anwhich they control so that the panel valve or valves may be shifted directly by means of dogs carried by the slide.

Panels 01 this. classare frequently utilized in constructing complex multiple head machines having a large number ofindependently movable machine slides; the actions of which are corre-' lated by means of a complex electrical circuit interconnecting thevarious control panels to provide a-completely' automatic cycle of operation during normal use.- In-constructing such an auiomatic machine it is necessary, however, to provide for manual operation of the machine slides individuallyduring setting-up operation, and it has lieen found, that, due to. the complex nature I of the electrical circuit during automatic operation, the addition of manual control entails considerable addltional'expense because of the necessity of providing extra relays and contactcrs to permit manual operation with complete safety. It is an object of the present, invention to provide a power transmission system incorporating a control panel of the general class described above having improved manualmea'ns for controlling the system independently of the automatic electric control circuit.

'. 'A further object is to provide in a panel of the-character describeda manual control suit switch 54 is adapted to supply current to a coninvention will be apparent from the following description, reference being had to the accom panylng drawing wherein a preferred form of the present invention is clearly shown.

other as a fluid motor. 5 In the drawing; 7 v The invention is more particularly concerned Figure l is a diagrammatic view of a powerwith a control panel of the class commonly used transmission system incorporating a preferred for actuating machine tool slides for providing form of the present invention.

v the customary cycle of rapid advance, feed ad- Figure 2 is a sectional view of the control panel vance, rapid return and stop of the machine tool 10 shown in Figure 1. x

--slide. Inthe patenttoHarrington,No.2,210,865, Figure 3 is a cross section on line 3+4 of granted August 6, 1940, there is disclosed a con- Figure 2. 4 I trol panel suitable for hydraulically operated ma- Figure 4 is a table of cycle functions and flow chine tools. The panel there disclosed presents paths for use in conjunction withFiguie 2.

certain advantages in the way of-adaptability i5 Referring now to F e 1. re is shown a pump Ill driven by an electric motor I 2 to withdraw fluid from a. tank -it through a-suction conduit i6. Fluid is delivered through a delivery conduit It. a relief valve 20 of conventional constructionbeing provided for bypassing fluid to thetank through a return conduit 22 whenever a predetermined pressure is exceeded in the delivery conduit i8. a

The conduit is leadsto a port 24 of a control panel 26. Aport 28 ofthe latter connects with the return conduit 22. The panel .26- is also provided with cylinder ports 30 and 32 which connect by conduits 3t and 36 with the upper and lower ends of a motor cylinder 38 The latter carries a slidable pistontil having a rod42 connected to a suitable machine tool slide indicated diagrammatically at 44. Secured to an upwardly extending arm 46 are two tripping dogs lliiv and 50 and a cam 52 adapted to actuate limit switches 54. 58 and 58, respectively, when the slide 44 is at the top, bottom and middle positions, respectively. i

The panel 26 is controlled by'two solenoids Gil and 82, respectively (see Figure '2), these solenoids in turn being under the control of an electric circuit including the previously mentioned limit switches. From one side of a suitable power source designated L the normally-closed limit ductor 84 which connects with both the normal- .ly-open and the normally-closed contacts of a holding relay 66. A normally-open, two-circuit,

starting pushbutton switch 68 is adapted to esable for setting-up operation and which precludes thepossibility ofaccidentalshifting'of the control panel into any position dangerous to the setting-up operation.

-- tablish a connection from line L to the coil of relay-ti and also tothe conductortLthese circults being independent when the switch- 68 is open. The opposite side of the coil of relay G6 is connected to the opposite side of the supply line lhe.holdingcontacts of the relay it are con trolled by a conductor I which has in series therewith both the limit switch 68 and a normally-closed emergencyreverse switch I2. The

' normally-open contacts of relay '88 connectbetween conductor 68 and a conductor 74 extending to one side of the solenoid 80, the other side 58 connects between conductor 64 and conductor I 18 by a conductor 18.

It will be seen that, when the starting button 68 is depressed, the holding relay 66 is energized to connect conductor 86 with conductor It. Si-

multaneously the lower contacts of push button 68 connect conductor 64 temporarily with line L thus establishing .a circuit for solenoid 60. A circuit is also established for solenoid62- from conductor 66 through limit switch 58, conductor 18 and conductor I6. As will be later described, energization of both solenoids causes the piston 40 to descend so that trip dog 58 rides of! limit switch 64 thus shunting the lower contacts of push button as and permitting the latter to be opened without deenergizing solenoid 60.

As the piston 40 descends, a point is reached where the cam 52 opens limit switch 58, thus deenergizing solenoid 62. The piston 60 will continue to descend, at a lower rate, however, until trip dog 50 opens limit switch 56 which in turn releases relay 66 thereby breaking the circuit 76 of solenoid 60.

Dropping of relay 86 also established a circuit for solenoid 62 from conductor 84120 conductor I6. As will be described later, this causes the piston 80 to return until trip dog 88 opens limit switch 54, thus breaking the connection between line L and conductor 66. It will be noted that during the latter portion of the upward movement of piston 40, limit switch 58 again rides off cam 52, This has no efiect, however, on the energization of solenoid 82-, since it is already energized by relay 66, and the closure of limit switch 58 merely establishes a sec- 0nd or shunt circuit between conductors 68 and The electric circuit thus far described is disclosed merely by way of example of a suitable circuit for controlling the energization of solenoids and 62, it being understood that in multiple unit machines more complex circuits 94 are formed in the bore 80, and corresponding ports 96, 98, I00, I02 and I04 are formed in the bore 82. Communication between the various ports is controlled by the piston heads formed on the valve members 84 and 86 in the well-known manner. The opposite ends of the bores are closed by providing oil seals I06 which are held in position by end caps I08 at the upper end of the bores and by an intermediate plate I I0 at the lower end of the bores.

The valve spools 86 and 84 have stem pro- .jecting through the oil seals, the lower stems being adapted to be engaged by the pushing end of the armatures H2 and H4 or the solenoids. 60 and 82, respectively. These armatures are provided with T-shaped heads IIB-and H8 in the well-known manner at their lower ends. The operating coils of the solenoids are secured to the intermediate plate IIO by suitable bolts or other fastening means.

The block 18 is also provided with a central bore 520 in which is positioned a hydrostatic flow controlling valve I22 which serves in conjunction with a manually adjustable throttle I24 to maintain a predetermined volumetric rate of flow through a conduit I26 which extends between port 98 and port I04. The throttle I24 may be adjusted by means of a knob and dial I28 which appears in Figure 1. The hydrostatic flow controlling valve and throttle operate in the well-known manner to maintaina constant pressure drop across thethrottle I24 thereby insuring a fixed rate of flow therethrough irrespective of the total pressure drop through the con-. duit B26.

The annular portsiof the bores and 82 are connected with each other and with the connection ports 28, 28, 80 and 32 by various internal passages which will be'described later in connection with the operation or the apparatus as a whole.

For the purpose of shifting the valve spools 84 and 86 selectively under manual control and independently of electrical energization of solenoids 60 and 62, there is provided a manually operable lever I30 secured to a cross shaft I32 in turn pivoted in a housing I34 which surrounds the two solenoids. The shaft 432 is provided with a hexagonal end I36 projecting from the front of the housing and on which a lever I38 may be positioned for manual oscillation of the lever I30. The two arms of the lever I30 extend beneath the heads H6 and II8 so that whenever the arm is moved'clockwise the head H6 will be raised and when it is moved counterclockwise the head il8 will be raised. For the purpose of normally biasing the lever I30 to its neutral position illustrated, a leaf spring I40 is secured to the bottom face of the lever I30 and overlaps the end of a slot I42 formed in the housing m. Theslot I42 is provided to permit downward movement of one arm of the I lever I30 while the other arm is raised.

-In operation, with the parts in the position as shown in the drawing and with the motor I2 and pump I0 running, the piston 40 will remain at rest and the pump I0 will be bypassed. The flow path through the panel under these conditions is indicated by the arrows carrying the numeral #3 at their head from which it will be seen that oil delivered through conduit I8 to port 24 flows through an internal passage I42 to the port 800 and from there to the port I02 where it flows through a passage I44 to the port of the valve bore-80. This oil returns to tank through longiv tudinal slots 146 formed on the valve spool 84 and through port 88, a passage I48, port 28 and conduit 22 to the tank.

When both solenoids 60 and 62 are energizedby depressing starting switch 68, the flow indicated by arrows numbered I is made to take place. Thus pressure oil entering at port 24 passes to port I00 and from there to port 08 where it passes to port 30'through a pasage I50.

2,28 end of cylinder 38 th1'ough conduit 36 to theport 32. This port is connected with port 92 by a passage I52, and from port 82 the oil flows to port 90 and through passage I44 to the port I02 of valve bore 82. Port I02 is at this time connected with port I04 from which the oil flows through a passage I54 to port 96 and through a advance rapidly. This arises fromthe fact that it is necessary to lift both valve spools 84 and 86 in order to cause the rapid advance function. This is impossible to do by the singlelever I and insures positive safety in the setting up operation making it impossible forthe operator to accidentally lift bothvalves and thus cause the machine slide to advance rapidly and cause damsolenoid 62. Under these conditions-the flow to the head end of cylinder 38 is the same as before, being indicated by arrows marked No. 2.

The return flow, however, entering the panel at port 32, flows through passage I52, ports 92 and 94, passage I26, hydrostatic valve I22, and throttle I24, into port I04 where it returns to tank.

as previously described. Under these conditions of flow the hydrostatic valve and throttle limit the rate of discharge from the lower end of cylinder 38, thus causing the piston 40 to move at a feeding rate. The excess delivery of the pump under these conditions is bypassed to tank through the relief valve 20.

age to the tools before it could be stopped. By shifting the lever I38 downwardly ihe valve spool is, of course, lifted causing the rapid return function to take place. During setting up operation a return movement at high speed is not objectionable since there is no possibili y of wrecking an expensive set of tools 'by accidentally backing the slide away too far.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.-

What is claimed is as follows: 1. In a hydraulic power transmission system for actuating a shiftablemember at rapid traverse and feed rates' in opposite directions, a control panel of the type havinga pair of two-position valves separately and jointly shiftable out of the normal position to'provide four different When the piston 40 has descended to the point where dog opens limit switch 56, solenoid is deenergized while solenoid 62 is energized.

The flow under these conditions is indicated by the arrows marked 3 from which it will be seen that pressure oil is directed from port 24 through passage I42, ports I00'and I02, passage I44, ports 90 and 82, passage I52, port 32, and conduit 36 to the lower end of cylinder 38. The piston 40 accordingly moves upwardly discharging oil through conduit 34, port 30, passage I50, ports 98 and 96, passage I56, port 88, passage I48, port 28 and conduit 22 to the tank.

.When the piston has moved fully upwardly, dog 48 opens limit switch 54, thus deenergizing solenoid 62 causing the piston 40 to stop and bypassing the discharge of pump I0 as previously described.

It will be seen that this cycle of operation can be made to take place automatically by the use of an electric control circuit which controls the energization of the solenoids in response to movement of the machine slide after the cycle has been initiated by the manual starting switch 68. When it is necessary to actuate the slide 44 under manual control, the electric circuit may be disabled by opening the usual main line switch, not shown, and the slide may be actuated forwardly, at a feeding rate only, by lifting the lever I38 which in turn lifts valve spool 86. Thus the slide 44 may be advanced slowly toward the work, and precise set-up of the tripping dogs with respect to the tool and work positions may be easily made.

It will be noted that it is impossible by actuation of the handle I 38 to cause the slide 44 to operating functions including a rapid advance with both valves shiftedfa feed advance with one valve shifted, a return with the other valve shifted and a stop of said member with neither valve shifted, individual electric actuators for said valves, a control circuit including circuit controllers actuated by the shftable member for providing said functions in sequence automatically, and manual means for shifting said valves to selectively provide either feedadvance or rapid return of said member, said means including a single lever normally biased to a neutral position in which both valves are freely shiftable by said actuators, said lever being shiftable to one side of neutral position to shift said one valve only and being shiftable to the other side of neutral position to shift the other valve only, whereby under manual control it is impossible to obtain a rapid advance of said member.

2; In a hydraulic power transmission system for actuating a shiftable member at rapid traverse and feed rates in opposite directions, a control panel of the type having a pair of two-position valves shiftable to provide four different operating functions, a pair of solenoids for actuating said valves, means responsive to shifting of the member for controlling energization of said solenoids, a removable housing surrounding said solenoids and having an elongated slot in one end, a straight lever pivoted in the housing adjacent the slot and adapted when manually oscillated to engage and shift either of the solenoids respectively, and a leaf spring secured to the lever adjacent its pivot and overlapping the edges of the slot, said spring biasing the lever to a neutral position parallel to the end of the housing.

' FERRIS T. HARRINGTON.

RALPH L. TWEEDALE. 

